An investigation into an oil spillage near Alfreton is continuing today.
The incident happened on Tuesday at Pennytown Ponds, Somercotes.
Specialist equipment is being used to collect the oil and the Environment Agency is on site continuing investigations into the possible cause.
Paul Reeves, of the Environment Agency in East Midlands, said: "The cleanup of oil has resumed and a joint investigation with Severn Trent to trace source of the pollution is ongoing."
No dead fish have been found.